Insert Coupling

ABSTRACT

An insert coupling more preferably intended for use with fuel lines consists of a sleeve-like coupling body ( 2 ) and a tubular insert part ( 1 ) carrying a retaining rib ( 3 ) on the outside. Via a coupling element ( 22 ) axially fixed in the coupling body ( 2 ) on to which engagement hooks ( 4, 4 ′) are moulded which are intended for engagement with the retaining rib ( 3 ), a ring shoulder ( 23 ) is formed at the same time which together with a ring shoulder ( 24 ) of the housing ( 8 ) of the coupling body ( 2 ) axially spaced from said ring shoulder and the radially spaced cylindrical faces of the housing ( 8 ) facing each other and the insert part ( 1 ) define a ring space ( 11 ) in which a sealing arrangement consisting of two sealing rings ( 5, 7 ) and a support ring ( 6 ) arranged in-between are accommodated. As a result of the unambiguous axial fixing of the sealing arrangement in the housing ( 8 ) the function of the sealing arrangement is not impaired through the removal of the insert part ( 1 ) from the coupling body ( 2 ) and through inserting said insert part in the coupling body ( 2 ). A simple construction of the insert coupling is obtained in that said coupling factually consists only of three substantial components plus the sealing arrangement and can be employed with insert parts ( 1 ) which are smooth-walled except for a retaining rib ( 3 ).

The invention relates to an insert coupling according to the preamble of claim 1.

Insert couplings of this type are utilized for example in vehicle construction with fuel lines and serve to establish a connection between a tubular insert part provided with a circumferential retaining rib and a sleeve-type coupling body. The insert part can be manufactured of plastic or metal and be the end of a line or the connection spigot on a housing. The coupling element is usually manufactured of plastic and mounted on a line but can also be a part of a housing.

Insert couplings of this type are characterized by a locking mechanism that is effective between the coupling body and the insert part and are intended to form a sealing connection between the respective line elements to be coupled. They have become known in numerous forms wherein particular attention has been attached to functional reliability and characteristics of assembly-related handling.

From DE 4300037 C1 an insert coupling of the type mentioned at the outset is known wherein the locking mechanism between the coupling body and the insert part is constituted of a component which is displaceable radially to the main axis and intended for engaging behind the retaining rib of the insert part. Comparable insert couplings are known from DE 197 22 842 C2, DE 10 2004 062 887 B3, EP 17 19 944 A2, US 2004/0189001 A1 and DE 10 2006 019 257 A1. With these insert couplings it is disadvantageous that correct engagement of the insert part in the coupling body is not definitely evident from the outside in all cases. The assembly of the insert couplings must take place in two directions so that the expenditure for automatic assembly is clearly increased. The number of necessary components is also high.

A further insert coupling is known for example from DE 44 13 346 C1, whose locking mechanism is realised through a sleeve which is axially inserted in the coupling body and axially displaceable to a limited extent in the slide-in position. The sleeve consists of a ring positioned in the sleeve base of the coupling body from which four webs extend parallel to the axis in even circumferential distribution and in the direction of the open end of the coupling body, of which two carry engagement hooks located diametrically opposite each other intended on the inside to interact with the retaining rib of the insert part. All webs are provided on the radial outside with shoulders which are accommodated axially moveable to a limited extent in recesses of the coupling body so that via two projections moulded on the outside to the webs not provided with engagement hooks and protruding from the coupling body the sleeve can be gripped and moved axially relative to the coupling body in order to release the coupled state of the insert part with the coupling body.

Disadvantageous with this insert coupling is that correct engagement is not visible from the outside. Furthermore, the sleeve forms an active surface for the seal embodied by means of O-rings. Owing to the required axial displaceability of the sleeve the inserted O-rings upon introducing the insert part are pushed into an axial end position and, upon the intended exposure of the coupling to internal pressure, into an opposite axial end position. In the front region, which the O-rings on their path have to cover, dirt is able to enter from the outside. The O-rings perform this displacement with every releasing and establishment of a coupled state so that there is a risk that the O-rings twist and/or dirt particles become embedded in the sealing regions during this movement as a result of which secure tightness is no longer guaranteed. This is all the more significant since this type of coupling among other things is also utilised in fuel lines. A leak test during series production upon the assembly of the coupling as a unit is not possible since the O-rings assume their active position only in the assembled state.

The insert coupling known from DE 39 29 723 is characterized by a sleeve part and an insert part provided with a circumferential retaining rib, wherein the sleeve part is material-connected with a ring-shaped shoulder part carrying an arrangement of reed-like restraining elements orientated from inwardly in the direction of the base of the sleeve part, and wherein in the coupled state these restraining elements are intended for the positive connection engagement behind the retaining rib. The shoulder part on its side axially facing away from the restraining elements forms an active surface for supporting a sealing arrangement, which is otherwise axially supported on the sleeve part. For releasing the coupled state a sliding sleeve is provided whose face end is intended and equipped for the radial engagement below the restraining elements and thus for the releasing of the engagement with the retaining rib of said restraining elements. This insert coupling is thus characterized by a multiplicity of components and thus by a comparatively complicated construction.

Finally a further insert coupling is known from DE 37 27 858 which consists of a sleeve-like coupling body on its one end intended for joining with a hose and an insert part intended for insertion in said hose intended for joining with a line at its end facing away. The end of the coupling body facing the insert part is characterized by a ring element on whose inside block-like locking segments are moulded which are intended for the positive engagement behind a holding rib circumferentially arranged on the insert part. The ring element is in connection with the coupling body by way of two webs which extend parallel with the axis and are located diametrically opposite each other, said ring element is further characterized by a cylindrical mounting space on the inside which interacts with two sealing rings each accommodated in slots of the insert part. Releasing of the coupled state is thus possible through the oval deformation of the ring element. This insert part requires utilisation of a special insert part which simultaneously acts as carrier of the sealing rings. A special assembly sequence is thus required. Although there are recesses between the mentioned webs—whether there is a correct state of engagement between the retaining rib and the locking segments is at least through mere inspection not easily detectable with adequate reliability.

It is the object of the invention to improve an insert coupling of the type named at the outset while maintaining its functionality and simple design structure with regard to its handling during assembly and simple detection of a perfect engaged state. This object is solved with such an insert coupling with the features of the characterizing part of claim 1.

Accordingly, a coupling element which can be inserted in the coupling body and fixed in its axial position is essential to the invention. This coupling element forms a first axial active surface for a sealing arrangement by way of a ring shoulder. Said coupling element also forms the carrier for the engagement hooks which are intended for interacting with the retaining rib. The coupling element is embodied with a view to visual detectability of a correct state of engagement between the coupling body and the insert part. Essential are therefore the establishment of a lateral recess and the positioning of the retaining rib and the engagement hooks with the stipulation that their engagement with the retaining rib within the recess is visually perceptible from the outside. According to the invention, the engagement hooks are attached to a ring element. This opens up simple possibilities of realising unlocking of the engagement of the engagement hook in the retaining rib in that the ring element is merely deformed radially. Together with a further ring shoulder formed through the housing of the coupling body a ring space is presented in connection with the cylindrical faces of the insert part facing each other and radially spaced from each other and the housing of the coupling body, in that the sealing arrangement is fixed axially non-displaceably and in accordance with elastic deformation is held in a sealing manner in contact with the mentioned faces. The function and the position of the sealing arrangement which can consist of at least one sealing ring is thus not impaired by an insertion of the insert part in the coupling body or through its removal from the coupling body. The insert part can be of a conventional cylindrical type with entirely smooth walls except for the retaining rib. It is evident that the insert coupling is characterized by relatively few components.

The features of claim 2 are directed at a further measure which is intended for the particularly simple verification of a correct state of engagement of the insert part in the coupling body.

The features of claims 3 and 4 are directed at an embodiment of the coupling element. Added to its already mentioned function as carrier of the engagement hooks it is added accordingly that said coupling element via its ring element exerts a centering function on the insert part. This is of major significance to a reliable sealing effect of reproducible quality.

The features of claims 5 to 7 are directed at a further embodiment of the coupling element, more preferably for it's fixing in or to the coupling body. It is particularly advantageous that the fastening state of the coupling element in the coupling body can also be established from the outside through mere inspection.

The invention is explained in more detail in the following making reference to the enclosed drawings which show preferred exemplary embodiments. It shows:

FIG. 1 a partial exploded view of the insert coupling according to the invention;

FIG. 2 a longitudinal section of the insert coupling according to FIG. 1 in the engaged state;

FIG. 3 a perspective front view of the coupling body for explaining the unlocking;

FIG. 4 an exploded representation of the insert coupling according to FIG. 1;

FIG. 5 a cross-sectional representation of the insert coupling according to a section plane V-V of FIG. 6;

FIG. 6 a lateral view of the insert coupling according to FIG. 1 in the engaged state.

The insert coupling shown in FIG. 1 globally consists of a tubular insert Part 1, a sleeve-like coupling body 2 and a coupling element 22, wherein in the representational form shown the insert part 1 is not yet inserted in the coupling body 2. On the insert part 1 one can see a circumferential retaining rib 3 and, exemplarily arranged as a pair, engagement hooks 4, 4′ on the coupling element 22, which engagement hooks are located diametrically opposite each other. Both the coupling body 2 as well as the insert part 1 are provided on their ends facing away from each other with exemplarily shown connections 12, 13 to which a pipe or a hose can be crimped or welded. However, other embodiments are also possibly, more preferably these connections 12, 13 can also be direct components of a housing or another component.

Except for its dimensioning, the insert part 1 is thus adapted to the coupling body 2 only through the retaining rib 3 and otherwise embodied smooth-walled on the outside.

FIG. 2 shows the engaged state of the insert coupling. When inserting the insert part 1 in the coupling body 2 its retaining rib 3 strikes an insertion bevel of the engagement hooks 4, 4′, as a result of which the latter are elastically deformed outward, so that the spacing of these hooks is increased and the insert part 1 can be further pushed in the direction of the engaged state. As soon as the retaining rib 3 is located behind the respective retaining edges 10, 10′ of the engagement hooks 4, 4′, these resiliently spring back so far that they come to bear against the smooth-walled outside of the insert part 1. This establishes a positive connection in axial direction between the insert part 1 and the coupling body 2.

The coupling body 2 is characterized by a tubular housing 8 whose inert diameter is designed larger than the outer diameter of the insert part 1, so that between these a ring space 11 is obtained in which in axial succession a first sealing ring 5, a support ring 6 and a second sealing ring 7 are accommodated. These rings are axially in contact with one another in the engaged state of the insert coupling, wherein a ring shoulder 24 limiting the ring space 11 on the side of the housing 8 facing the connection 12 and extending radially forms an axial active face for the sealing ring 7.

On inserting the insert part 1 its free end is guided by the sealing ring 5, the support ring 6 and the sealing ring 7 within the ring space 11 of the housing 8. The sealing rings 5, 7 are elastically deformed in the process and are radially tensioned between the cylindrical inner and outer walls of the ring space 11, thus between the sides of the housing 8 facing each other radially and the insert part 1 so that they seal the ring space 11 with respect to the outer space of the coupling body 2. The support ring 6 separates the two sealing rings 5 and 7 in order to obtain separate sealing regions for each sealing ring 5, 7. At the same time, the insert part 1 is centred in the ring space 11 of the housing 8.

The sealing ring 7 and the support ring 6 can be optionally employed when extremely great tightness and redundancy is demanded. Principally speaking, a single ring-shaped sealing element is adequate at that point.

As is evident when viewing FIGS. 3 and 4 together, the coupling element 22 consists of a ring body 15 whose one side facing the connection 12 in the engaged position forms a ring shoulder 23 which forms an axial active face for the sealing ring 5. The arrangement consisting of the sealing rings 5, 7 and the support ring 6 is thus axially clamped between the active faces represented by the ring shoulders 23, 24 and unambiguously fixed in its position.

On the ring body 15, specifically on its side axially facing away from the ring shoulder 23, two cylindrical straps 17 extending parallel to the axis and located diametrically opposite each other are moulded between which, in each case subject to retaining slots 25, two cylindrical webs 26 likewise located diametrically opposite each other extend, on the free ends of which facing the insert part 1 the mentioned engagement hooks 4, 4′ are moulded-on radially inside. The webs 26 are otherwise characterized by a step 27 emanating from the radial level of the ring body 15 and extending to the outside.

Elastically resilient connection elements are designated 22′, 22″, 22′″, 22″″, which are moulded on to points of the free ends of the webs 26 located radially on the outside and together with these form a polygon-like ring element 28 with lateral segment-like unlocking elements 14, 14′ located opposite each other and embodied identically. In the installed state of the coupling element 22, which will be still explained in the following, the radially outside likewise segment-like engagement hooks 4, 4′ partially protrude into recesses 29 of the housing 8 which are moulded into the face end 30 of said housing facing the coupling element 22.

A possible advantageous unlocking mechanism is shown in FIG. 3. For unlocking, forces are exerted on the unlocking elements 14, 14′ in the direction of the arrows F and F′. Via the connecting elements 22′, 22″, 22′″, 22″″, these forces act on the engagement hooks 4, 4′ in the form that the latter are elastically deformed outwardly in the direction of the arrows S because of the symmetry characteristics of the ring element 28. Because of this movement, the positive connection in axial direction between the insert part 1 and the coupling body 2 is released. The insert part 1 can now be pulled out of the coupling body 2.

FIG. 4 shows all components of the insert coupling in an exploded view. 16, 16′ (FIG. 5) designates engagement cylinders which are moulded to the outside of the straps 17 in positions located opposite one another extending perpendicularly to a longitudinal axis of the ring element 15.

To assemble the components of the insert coupling, the sealing ring 5 is first inserted in the housing 8, thereafter the support ring 6 and finally the sealing ring 7. As last component the coupling element 22 is inserted in the housing 8. Alternatively to this, all of these components can also be mounted on an assembly mandrel which is then jointly inserted in the housing 8. The substantial part is that all of these components can be inserted in the housing 8 in an axial movement.

During this insertion movement, the engagement cylinders 16, 16′ strike the inside of the wall of the housing 8. Through an insertion bevel 20 provided at its face end the straps 17, 17′ are elastically deformed radially inwardly so that the coupling element 22 can be further inserted in the housing 8. On the further displacement path the engagement cylinders 16, 16′ come into a congruent position with radial bores 19, 19′ of the housing 8. Because of the elastic preload of the straps 17, 17′ the engagement cylinders 16, 16′ are inserted in the bores 19, 19′ and form a positive connection, so that the position of the coupling element 22 in the housing 8 is axially secured. Since the bores 19 are openly accessible from the outside of the housing 8 the engaged state of the engagement cylinders 16, 16′ and thus the correct fixing of the coupling element 22 within the coupling body 2 are verifiable through mere external inspection.

In this secured position of the coupling element 22, its ring shoulder 23 forms an active face for the sealing ring 5. At the same time the ring element 15 of the coupling element 22 centres the insert part 1 in the housing 8. Because of the axial and radial fixing of the coupling element 22 in the housing 8, active faces are defined axially on both sides of the arrangement of the rings 5, 6, 7 between which this arrangement is axially secured.

The installation state of the coupling element 22 characterized by an engagement of the two engagement cylinders 16, 16′ in the bores 19 is further characterized in that in the engaged state of the insert coupling the face ends 28′ of the ring element 28 and 17′ facing each other of the straps 17 are held in accordance with a spacing 31 relative to each other. A retaining edge 10, which is intended as respective integral part of the engagement hooks 4, 4′ directly for engaging behind the retaining rib 3 is axially located at a point within the mentioned spacing 31.

FIG. 6 shows a completely engaged insert coupling according to the invention. The duly engaged position of the retaining edge 10 can be visually seen behind the retaining rib 3 since the axial position of the retaining edge is positioned within the recess 29 defined by the spacing 31.

It is further evident that with a correctly engaged position of the engagement hook 4 its radial outside closes off flush with a housing edge 21 of the housing 8. With incorrect engagement of the engagement hook 4 the retaining edge 10 rests on the outer diameter of the retaining rib 3 so that the engagement hook 4 is radially deformed beyond the housing edge 21, a circumstance that can be detected visually and also through touch.

There are thus two mechanisms of an engagement check which act independently of each other. 

1: An insert coupling consisting of a tubular insert part (1) having a circumferential retaining rib (3), a sleeve-shaped coupling body (2) provided with at least one engagement hook (4, 4′) intended for the positive engagement with the retaining rib (3) and a sealing arrangement inserted in a ring space (11) between the insert part (1) and a housing (8) of the coupling body (2), wherein the at least one engagement hook (4, 4′) is radially moveably arranged in a position which establishes engagement with the retaining rib (3) and releases said engagement, wherein the engagement hook (4, 4′) is moulded on to a coupling element (22) which can be axially inserted in the housing (8) and axially fixed in an insert position, wherein the ring space (11) is limited by a ring shoulder (23) formed through an axial face end of the coupling element (22) and in the mentioned insert position axially spaced from said ring shoulder (24) is limited by a radial step of the housing (8), so that the ring shoulders (23, 24) form axial active faces of the sealing arrangement and wherein the ring space (11) is otherwise represented through the cylindrical smooth, radially spaced surfaces of the housing (8) facing each other and the insert part (1), characterized in that the coupling element (22) consists of a ring element (15) on which webs (26) are arranged parallel to the axis, on whose ends the engagement hooks (4, 4′) are moulded on radially on the inside, wherein the engagement hooks (4, 4′) together with connecting elements (22′, 22″, 22′″, 22″″) and unlocking elements (14, 14′) form a ring element (28), that the engagement hooks (4, 4′) are accordingly arranged distributed along the circumference of the ring element (28), that through radial deformation of the ring element (28) the engaged state of the engagement hooks (4, 4′) can be released with the retaining rib (3), that on the ring body (15) straps (17) parallel to the axis are moulded which extend away from the coupling body (2) in a direction and are spaced from the webs (26) through slots (25), that axially between the face ends (28′) of the ring element (28) and (17′) of the straps (17) facing each other a space (31) is established and that during a coupling state the retaining rib (3) including the retaining edges (10) of the engagement hooks (4, 4′) engaging behind the former in a recess (29) are visible whose axial width corresponds to the spacing (31) so that the intended engagement of the retaining edges (10) moulded on to the engagement hooks (4, 4′) with the retaining rib (3) of the insert part (1) is visible from the outside.
 2. The insert coupling according to claim 1, characterized in that the intended engagement of the retaining edges (10) moulded on to the engagement hooks (4, 4′) with the retaining rib (3) of the insert part (1) can be felt by touch from the outside because of the fact that an outside of the engagement hook (4, 4′) extends flush with an adjoining edge (21) of the housing (8) of the coupling body (2) and does not protrude over the housing edge (21) of the housing (8).
 3. The insert coupling according to claim 1, characterized in that the ring element (15) is configured with a view to centering the insert part (1).
 4. The insert coupling according to claim 1, characterized in that a free face end of the ring body (15) constitutes the ring shoulder (23).
 5. The insert coupling according to claim 1, characterized in that the coupling element (22) in its inserted position is engaged with the housing (8).
 6. The insert coupling according to claim 1, characterized in that the straps (17) on the outside are carriers of engagement cylinders (16) which are intended for the engaging of the coupling element (22) with the housing (8).
 7. The insert coupling after plug connection according to claim 1, characterized in that the engagement state of the coupling element (22) with the housing (8) is visually visible from the outside.
 8. The insert coupling according to claim 2, characterized in that the ring element (15) is configured with a view to centering the insert part (1).
 9. The insert coupling according to claim 2, characterized in that a free face end of the ring body (15) constitutes the ring shoulder (23).
 10. The insert coupling according claim 3, characterized in that a free face end of the ring body (15) constitutes the ring shoulder (23).
 11. The insert coupling according to claim 2, characterized in that the coupling element (22) in its inserted position is engaged with the housing (8).
 12. The insert coupling according to claim 3, characterized in that the coupling element (22) in its inserted position is engaged with the housing (8).
 13. The insert coupling according to claim 4, characterized in that the coupling element (22) in its inserted position is engaged with the housing (8).
 14. The insert coupling according to claim 2, characterized in that the straps (17) on the outside are carriers of engagement cylinders (16) which are intended for the engaging of the coupling element (22) with the housing (8).
 15. The insert coupling according to claim 3, characterized in that the straps (17) on the outside are carriers of engagement cylinders (16) which are intended for the engaging of the coupling element (22) with the housing (8).
 16. The insert coupling according to claim 4, characterized in that the straps (17) on the outside are carriers of engagement cylinders (16) which are intended for the engaging of the coupling element (22) with the housing (8).
 17. The insert coupling according to claim 5, characterized in that the straps (17) on the outside are carriers of engagement cylinders (16) which are intended for the engaging of the coupling element (22) with the housing (8).
 18. The insert coupling after plug connection according to claim 2, characterized in that the engagement state of the coupling element (22) with the housing (8) is visually visible from the outside.
 19. The insert coupling after plug connection according to claim 3, characterized in that the engagement state of the coupling element (22) with the housing (8) is visually visible from the outside.
 20. The insert coupling after plug connection according to claim 4, characterized in that the engagement state of the coupling element (22) with the housing (8) is visually visible from the outside. 